It is known in the silver halide photographic art that color images having improved sharpness (acutance) can be obtained through the use of development inhibitor releasing compounds. Development inhibitor releasing compounds are often refered to as DIR compounds, which term is used here to include compounds which release an inhibitor containing group with a timing group (often referred to as DIAR compounds). Such compounds react with oxidized color developer (in particular, oxidized primary amino developing agent) to form a colored or non-colored compound while releasing a development inhibitor or a development inhibitor precursor. DIR compounds are to be distinguished from compounds which inhibit development upon exposure of the element to a black and white developer. The use of particular DIR compounds is described, for example, in U.S. Pat. Nos. 4,857,440; 5,006,448; 4,729,943; and EP 0,329,016.
Another means for improving acutance in silver halide film elements, has been the use of a dye which absorbs light in the region to which a particular layer is sensitive and which is placed in or above that layer. It is known that improved acutance of color images can be obtained by addition of water soluble absorber dyes to color negative elements. In addition, combinations of diffusible dyes and DIRs in color negative film are known. The combined use of such a non-diffusible dye in combination with a DIR to improve image sharpness has also been described, particularly in negative working elements, in U.S. Pat. No. 4,855,220. U.S. Pat. No. 4,746,600 also discloses the use of a non-diffusible dye and DIRs to improve image sharpness.
A serious difficulty with the foregoing art is that while DIR compounds in the form of couplers have been employed successfully in negative photographic elements, they have met very limited success in reversal photographic elements. One of the reasons for this is that negative elements are only processed in a color developer to produce a negative dye image. On the other hand, reversal elements are first processed in a black and white developer followed by a fogging step, then a color developer. Currently, the standard process for processing reversal films is the Kodak Process E-6.RTM. development described in more detail below, or substantially equivalent processes made available by other manufacturers. Such processes use exhaustive color development. As described by T. H. James, ed., The Theory of the Photographic Process, 4th Edition, Macmillan, New York, 1977, page 611, exhaustive color development results in DIR couplers having little effect in color reversal materials. Similarly, U.S. Pat. No. 4,788,132 indicates DIR compounds are not effective in color reversal elements in the statement that the use of a DIR coupler in color reversal materials does not produce any substantial interimage effect since color development is hardly inhibited. While U.S. Pat. No. 4,729,943 describes the use of DIR couplers in color reversal elements, the DIR coupler is incorporated in a layer which does not take part in image formation and the color development time is reduced to between 1 and 2 minutes (that is, the development process is non-standard).
For purposes of this invention, conventional development processes include the E-6 process as described in Manual For Processing Kodak Ektachrome Films Using E-6, (1980) Eastman Kodak Company, Rochester, N.Y., or a substantially equivalent process made available by a company other than Eastman Kodak Company, are referred to as "current" color reversal processes or "standard" processes. Current reversal processes employ as a color developer, 4-(N-ethyl-N-2-methylsulfonylaminoethylino)-2-methylphenylenediamine sesquisulfate, 1-hydrate in a concentration of from about 7 to about 11 grams per 1000 ml of water, and as a silver halide solvent, 2,2-ethylenedithioethanol (also known as Dithiaoctanediol) in a concentration of about 0.6 to about 1.2 grams per 1000 ml of water. The pH of the color developing agent is from about 11.6 to about 12.1. The color developing agent is used in the process for about from 5.5 to 7.0 minutes at a temperature of from 36.6.degree. to 39.4.degree. C.
It should be noted at this point that color reversal films have higher contrasts and shorter exposure latitudes than color negative film. Moreover, such reversal films do not have masking couplers, and this further differentiates reversal from negative working films. Furthermore, reversal films have a gamma generally between 1.5 and 2.0, and this is much higher than for negative materials.
It would be desirable then to have a color reversal film with enhanced acutance but which can still be processed through standard color reversal processes (which, as described above, are exhaustive).